JPH05203639A - Method and apparatus for separating blood into component - Google Patents

Abstract

PURPOSE: To extremely reduce the mixing with a leucocyte by alternating the interface between fractions between at least two positions to move the same during the first separation process due to centrifugal separation. CONSTITUTION: A blood centrifugal separator has a separation chamber 1 for the first separation step and whole blood VB is roughly separated into two phases herein. The first fraction contains blood cells, especially, blood corpuscles and white corpuscles. The second fraction is composed of blood plasma PRP especially rich in platelets. A phase detector 3 catches the interface between both fractions. In the second separation step, the blood plasma fraction PRP is supplied to a sampling chamber 4 through a pump 5 and separated in order to obtain a platelet concentrate TK. A program adjusting device 6 adjusts the pump 5 so that the interface between both fractions is alternately moved between at least two positions during a separation process in the separation chamber 1. By the alteration of this interface, blood plasma PRP rich in platelets is transported to the second separation step and the mixing with white corpuscles is almost perfectly excluded.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method and apparatus for separating blood into components by density centrifugation.

[0002]

2. Description of the Prior Art In the prior art, the interface monitored in the first separation step causes the blood to be at least roughly separated into two phases, of which the first fraction is mainly blood cells, and secondly the second. The fractions consist mainly of platelet-rich plasma, and in a second separation step one of the fractions is further separated to obtain a concentrate of blood components.

An apparatus for separating blood into its components by density centrifugation according to the prior art has a separation chamber of the first separation step, in which the blood to be separated via a blood pump is introduced from the inlet side. In the separation chamber, blood is at least roughly separated into two phases, in which the first fraction consists mainly of blood cells, the second fraction mainly consists of platelet-rich plasma, and between both fractions. The apparatus has a facility for capturing an interface, the apparatus has a collection chamber for the second separation step, the collection chamber is supplied with a platelet-rich plasma fraction via a plasma pump, and the fraction is collected in the collection chamber. Is further separated to obtain a concentrate of blood components, and further the centrifuge device has a program control for operating the device including speed adjustment of the plasma pump. Preferably 2
In the second separation step the platelet rich plasma fraction is further separated to obtain a platelet concentrate.

An apparatus of this kind is, for example, the applicant Fresen.
ius AS 104, Baxter CS 3000
Known by the cell separators of the company or the Cobe Spectra company.

[0005]

For the treatment of patients with specific diseases, specific blood components supplied to the patient are required. For example, platelet concentrates are needed for the treatment of patients with platelet deficiency.

On the other hand, the blood of the donor connected to the extracorporeal circuit is subjected to density centrifugation in a blood centrifuge and separated into its components. During the blood separation, the blood is roughly separated into two phases in the first step, namely a dark red cell-enriched fraction mainly consisting of red blood cells and a bright yellow fraction mainly composed of platelet-rich plasma. To be separated.

The position of the limit of both phases is monitored by a locator and adjusted, for example by a plasma pump. In that case, when the amount of cells exceeds the amount of plasma rich in cells, it is called a high-level interface, and when it is the opposite, it is called a low-level interface.

In the known procedure for obtaining platelet concentrates, in the customary model, the position of the interface is then kept constant at the desired position during the post-separation separation period.

If a platelet concentrate is to be obtained, the platelet-rich plasma is separated in a second step into platelet-poor plasma and the desired platelet concentrate. The platelet concentrate serves to treat the patient and the remaining components of the blood are recombined and provided to the donor.

A standard platelet concentrate consisting of about 3 to 4 × 10 ¹¹ cells should be obtained with the least possible separation period, the highest yield and the least possible leukocyte contamination. For leukocytes trigger a defense mechanism in a non-self body, here the patient's body. This leads to the immunization of patients, who can significantly limit the effectiveness of subsequently provided drugs.

The lymphocytes of the white blood cell subfraction are
Although decisive for the induction of defense mechanisms, platelets cannot be reliably separated from one another by centrifugation by known procedures, due to only small differences in size.

Therefore, to ensure that immunization is avoided by current techniques, further filtration is performed to separate the leukocytes from the platelet concentrate before delivery to the patient. Similar treatments are performed on other blood components.

The known operation therefore has the disadvantage that it requires additional processing steps in a further separating device, which results in high expenditures and costs and in terms of maintaining sterility. is there.

The problem underlying the invention is to develop a method and device as initially described, so that platelet concentrates can be readily obtained which are particularly low in blood constituents and therefore no longer required to be filtered. ing.

[0015]

According to the method of the present invention, the object is to move the interface between both fractions alternately between at least two positions during the separation process of the first separation step. Resolved

In the device according to the invention, the program adjustment 6 represents an adjustment section for the plasma pump 5, in which the interface between both fractions in the separation chamber 1 alternates between at least two positions during the course of the separation. The solution is successful because the adjustment section is formed to move.

Due to the alternation of the interfaces in the first separation step, in the case of the acquisition of platelet concentrates, only the platelets due to the platelet-rich plasma are transported to the second separation step, thus almost completely eliminating the leukocyte contamination. It is possible.

In the first type of blood cell separator, the working species is known to have a certain separation limit given above, in which case the working species is subsequently reversed again to the first working species. Therefore, the plasma pump is operated at a high speed for a short time with respect to the blood pump.

In this "overflow" type of working species, the platelet-rich plasma fraction (PRP fraction) overflows and exceeds red blood cells. During this time, the plasma pump of the blood cell separator is operated at a high speed and stops, for example, when it perceives an increase in cell density or after the transfer of a given fractional volume to be collected. Thus, in this overflow mode of operation, the interface collapses due to the subsequent readjustment of the previously given constant value.

On the contrary, in the method of operation of the "alternate separation limit" according to the invention, the separation limit fluctuates periodically between two constant positions. The flow rate of plasma changes only while the separation limit changes.

PR at the positions of both fixed separation limits
The P fraction is transported to the second step and blood cells are extruded from the separation chamber of the blood cell separator via the second outlet and returned to the blood supplier. The procedure also applies to the acquisition of cell mixtures of other cell types by separation of other biological solutions.

[0022]

The present invention will be described in detail below with reference to the drawings and examples.

The acquisition of platelet concentrates is described as an example. The operations and devices for separating blood into its components by density centrifugation are known. These are, for example, US Pat. No. 3,655,123, 4,056,224,
It is known from 4 108 353. Equipment for monitoring the interface in such a separation device (blood centrifuge) is disclosed, for example, in EP 116716 (EP-P).
known from dent-schrift 116 716). Therefore, the understanding of the invention is sufficient based on the drawings.

FIG. 1 shows diagrammatically the distribution of the phases of blood centrifugation at the lower separation limit 1 depending on the separation period t. A layer of separated blood components is formed over the course of the separation. A relatively wide platelet layer 6 is formed on the white blood cell layer 8 on top of the red blood cell 2 to form a lower layer of a layer of plasma 4 rich in platelets. A hypothetical ideal state of the interface between platelets and white blood cells is shown.

It has been shown in practice that a relatively wide platelet layer can form a barrier to the white blood cell layer. The red blood cells are supplied again to the donor 10, and only the platelet-rich plasma 4 is transferred to the second separation step. In this step, the platelets are concentrated (position 12) and the plasma is low in platelets 1
4 is returned to the donor 10 from the first step after mixing with the red blood cells 2.

FIG. 2 illustrates the distribution of separated components at higher interfaces. The relevant symbols are selected as in FIG. The interface 1, also called the separation limit, is moved and adjusted by known means, for example by various extractions of the plasma fraction by a plasma pump.

In contrast to the separation at the lower interface (FIG. 1), the layer of platelets 6 forms a relatively small barrier to the layer of white blood cells 8 (white blood cells). Sedimentation of blood cells is difficult due to the relatively high flow rate in the plasma layer. Particularly for these reasons, the contamination of the blood plasma 4 rich in platelets with the white blood cells 8 inevitably occurs relatively easily.

The composition of the cell concentrate throughout the separation period changes within the first separation step. Table 1 shows the percentage division of the blood fraction depending on the treated blood volume at the position of the intermediate separation limit, the abbreviations used for the blood fraction having the following meanings. PRP = platelet rich plasma; PLT = platelets; WBC = white blood cells; RBC = red blood cells.

[0029]

[Table 1]

According to Table 1, when the position of the separation limit is constant, the blood volume increases and the intermediate layer mainly composed of platelets and white blood cells accumulates in the separation chamber. Plasma is removed for conditioning the interface and red blood cells are forced out of the separation chamber of the blood centrifuge.

Experience has shown that the loss of platelet yield in the second step is associated with a certain lower separation limit in the first separation step. On the other hand, here, the migration of leukocytes is interrupted, which ensures a low leukocyte contamination in the platelet concentrate.

When the separation limit is constant and high in the first separation step, the number of platelets in the second step increases. However, the white blood cell count and thus the contamination in the platelet concentrate is also increased. When the interface is extremely high, the contamination increases dramatically as shown in the following table.
The following table shows the efficiency of platelet apheresis and leukocyte contamination (WBC) at the positions of the invariant and alternating separation limits.

[0033]

[Table 2]

The high flow rate in the plasma layer precludes the deposition of platelets and the swirling that results in a high degree of mixing with the white blood cell layer results in the transfer of white blood cells with the platelets to the second step. Separation efficiencies for platelets reach a maximum, but contamination is 100 times higher in extreme cases. The ratio between the yield and the supply of the desired cell type is expressed here in% and is referred to as the separation efficiency. The donation of a cell type is quantified by determining the average concentration of the cell type in the donated blood volume, and the yield is determined by determining the concentration of the resulting concentrate in the cell type.

In the operating method according to the invention, the sampling time and the transfer time are produced by alternating and converting the separation limit position between at least two positions during the separation duration in the first separation step. Adjusting from the lower separation limit to the higher limit during collection results in the deposition of platelets in the interphase. The major part of the platelets is transferred to the second step in succession with the platelet-rich plasma. Separated cells are extruded from the separation step.

At the transfer time, the interface rises significantly so that the platelets collected in the first step overflow together.
A certain residual content of the platelet layer remains in the chamber, preventing leukocyte invasion.

Although the efficiency of the separation is somewhat reduced by the manipulation of a constant platelet volume, leukocyte contamination is kept below the critical immunity limit and further purification steps are avoided.

FIG. 4 is a schematic plot of platelet concentration on the ordinate versus separation period on the abscissa, showing alternating interfaces according to the invention. FIG. 3 shows the corresponding diagram, but according to the state of the art, the interface has a constant position in the first separation step. A comparison of the two schematic diagrams clearly shows an increase in platelets in the range of the metastatic layer (Fig. 4).

Leukocytes are removed from the chamber via the cell outlet by the initial lower separation limit, and by the change in the position of the separation limit and the resulting change in flow conditions in the chamber.

In this way, there is no risk of contamination of the platelet-rich plasma and thus of the subsequently obtained platelet concentrate during the high separation threshold times.
However, the content of platelets transferred to the second step in the phase is necessarily increased, as shown in FIG.

In FIG. 4, the time of the higher separation limit, designated the transition phase, is relatively short compared to the time of the lower separation limit, designated the collection phase in FIG. I mean,
This is because, among other things, leukocyte aggregation has already started anew during this time.

The study of convenient phase lengths and separation limit positions can be carried out empirically and is thus given in advance to the respective separation program of the separation device.

A blood centrifuge is shown in FIG. 5 with which the operation according to the invention is advantageously carried out. Only a substantial part of the centrifuge is shown for a better overview.

The blood centrifuge, also named blood cell separator, has a first separation step, namely blood pump 2
It has a separation chamber 1 capable of transporting the blood to be separated from the entrance via so-called whole blood VB.

In this separation chamber 1, whole blood is roughly separated into two phases. The first fraction consists of blood cells, in particular red blood cell RBCs. The second fraction consists of plasma PRP, which is especially rich in platelets. Details for the other individual fractions and their dependent changes on the separation period are understood from FIGS. 1 and 2 in connection with Tables 1 and 2.

A facility 3 for capturing the interface between both fractions, a so-called phase detector, is attached to the separation chamber 1.

The blood centrifuge further has a second separation step, the collection chamber 4, to which the platelet-rich plasma fraction PRP is fed via the plasma pump 5. In the collection chamber the PRP fraction is further separated to obtain platelet concentrate TK.

The centrifuge also owns the program regulator 6 and is conventionally made by a microprocessor. The regulator is connected to all the necessary sensors and actuators of the blood centrifuge to regulate the overall operating conditions. The connection between the phase detector 3 and the program adjuster 6 and the connection from this adjuster to the plasma pump 5 is such that the flow rate of the plasma pump changes as soon as the interface position shifts or is about to shift.

The adjustment of the interface between both fractions in the separation chamber is carried out by the advantageous conditions of the situation between the plasma and blood pump flow rates.

If the basal blood centrifuge is at the lower separation limit, the blood and plasma pumps will proceed at the initial ratio given above (eg 50/20). If the interface is to be advanced higher, the ratio must be modified for plasma rate of progression. The program coordinator then takes over the required coordination. For this reason, plasma pumps are usually operated at high speeds. Upon reaching the upper limit of the predetermined separation limit, the pump will proceed at its original ratio (eg 50/20) immediately.

Adjustments are made in inverse proportion when reducing travel. Plasma pumps are adjusted to lower pump speeds,
Therefore, pump up a little until the lower separation limit is reached.

According to the invention, the program regulator presents an adjustment section for the plasma pump 5, which in the separation chamber 1 is the interface between both fractions between at least two positions during the separation process. It is designed to move in alternation. The adjustment section then has a first part for adjusting the low to the upper limit and a second part for adjusting the significantly higher limit. At this time, the first time segment that is the sampling part is the transfer segment 2
Longer than the second time segment.

The adjustment of the blood centrifugation operation is also possible in accordance with the amount of accumulated platelets of each individual donor, whereby individual differences in the blood of the donor, such as platelet size and platelets, can be obtained. Concentration etc. are considered.

[Brief description of drawings]

1 is an illustration of the distribution of phases in a blood centrifuge at the lower interface.

2 is a diagram corresponding to FIG. 1, but at a higher interface.

FIG. 3 is a diagram in which the platelet concentration is plotted on the vertical axis against the separation period on the horizontal axis at a constant interface position according to the conventional technique.

FIG. 4 is a drawing corresponding to FIG. 3 but with alternating interfaces according to the present invention.

FIG. 5 is a block diagram of a blood cell separator (blood centrifuge).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Heninck Blass, Germany 6650 Homburg, Ostlink 75

Claims (9)

[Claims] 1. In a first separation step blood is at least roughly separated into two phases, the first of these phases
Fraction of blood is mainly composed of blood cells, the second fraction is mainly composed of platelet-rich plasma, and one of the fractions in the second separation step densifies the blood which is further separated to obtain a blood component concentrate. In the operation of separating into its constituents by centrifugation, in the first separating step the interface between both fractions is moved between at least two positions in an alternating manner during the separation process. Separation method by density centrifugation. 2. Operation according to claim 1, characterized in that the lower to higher interfaces are adjusted for the first time segment and the significantly higher interfaces are adjusted for the second time segment. Law. 3. The operating method according to claim 2, wherein the first sampling section is longer than the second transfer section. 4. The operating method according to claim 3, wherein the examination of the time segment and / or the interface position is performed empirically. 5. Method according to claim 3, characterized in that the determination of the time segment and / or the interface part is carried out automatically depending on the amount of the blood component to be obtained which has been accumulated. 6. Operating method according to claim 3, 4 or 5, characterized in that at least two sampling time sections and at least transfer sections are pre-equipped in succession for the continuation of the separation. 7. A device for separating blood into its constituents by density centrifugation and carrying out the method according to one of claims 1 to 6, wherein the centrifuge device is a first device. A separation chamber (1) for the separation step of which blood to be separated is supplied via a blood pump (2) in which the blood is roughly separated into at least two phases,
Of those phases, the first fraction consists mainly of blood cells and the second fraction mainly consists of platelet-rich plasma, and the centrifuge comprises a collection chamber (4) for the second separation step. To which a platelet-rich plasma fraction is supplied via a plasma pump (5), and in this collection chamber the fraction is further separated to obtain a concentrate of blood components, 5) In a centrifuge with a program regulator for the operation of the device, including regulation of the pump speed, the program regulator (6) has a regulating part for the plasma pump (5), Separation device according to 1), characterized in that during the separation process the interfaces are made to move in an alternating manner between at least two positions between both fractions. 8. The adjusting section according to claim 7, characterized in that the adjusting section has a first time section for adjusting the low to high interface and a second time section for adjusting the particularly high interface. Equipment. 9. The apparatus of claim 8, wherein the first sampling section is longer than the second transfer section.